An image processing apparatus uses a technique of converting the format of a color difference signal, which increases the number of pixels of color difference signals per one screen to the same as that of a luminance signal in a vertical or horizontal direction (refer to Jpn. Pat. Appln. KOKAI Publication No. 2008-236622).
This patent application discloses a technique of converting Moving Picture Experts Group (MPEG) 4:2:0 format (luminance signal horizontal-to-vertical pixel ratio 480:720; color difference signal horizontal-to-vertical pixel ratio 240:360) to 4:2:2 format (luminance signal horizontal-to-vertical pixel ratio 480:720; color difference signal horizontal-to-vertical pixel ratio 480:360).
In digital television broadcasting, a digital television signal is transmitted in an interlaced format in most cases. In the 4:2:2 format, a pixel position of a color difference signal basically has a phase offset in the vertical direction with respect to a pixel position of a luminance signal. Thus, when the 240:360 horizontal-to-vertical pixel ratio is simply converted to the 480:360 ratio to convert the format, the phase offset is disturbed. As a result, a color shift may occur in a color picture on a screen. A disturbed phase offset of a color difference signal has a great influence on the color picture of a display unit using a 4:2:2 format interlaced signal.